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Sensitivity Analysis and Evaluation of Enhanced Geothermal Systems (EGS): Integrating Subsurface Simulation, Economics and Case Studies
No full textGeothermal energy has the potential to become a significant contributor to the effort toward energy transition because it is environmentally benign (i.e., carbon-free), renewable, and practically inexhaustible if managed properly. Geothermal energy can be extracted from different geological formations, ranging from low-temperature ones occurring at shallow depths -- suitable for heating and cooling applications -- to high-temperature reservoirs deep at kilometer-scale depths for power generation.
This study focuses on the deep geothermal systems that are referred to as Enhanced Geothermal Systems, EGS. Energy recovery from EGS involves drilling deep injection and production wells to reach deep, generally low-permeability geologic strata, and hydraulically fracturing the high-temperature rocks while ensuring communication between injectors and producers. Cold water injected into the reservoir is heated by the hot rock with which it comes in contact and is then recovered as a high-temperature fluid (liquid and/or vapor) at the production wells. Appropriate management ensures the long-term viability of this of semi-closed loop system.
In this research, I investigated in detail the thermo-hydraulic behavior of EGS by modeling the transport of fluid and heat in the subsurface by means of numerical simulation using a scientific code. I first analyzed in detail the behavior and performance of a base case model involving a representative (realistic) EGS reservoir. I then conducted (a) a thorough sensitivity analysis by varying key reservoir properties and operational practices that control/affect the behavior of the system and its efficiency, as well as (b) a techno-economic analysis based on the results of the numerical investigation studies. With the insight gained from the base and the sensitivity analysis studies, I investigated the feasibility and performance of a geothermal system at the RELLIS campus of Texas A&M University using existing data derived from earlier oil and gas recovery operations at the site. Finally, I include in this dissertation a full field-scale analysis of a geothermal system that I performed as part of an internship project at SLB (previously known as Schlumberger), an oilfield services company.
The main finding of the study is the importance of a heat-exchange surface area in the reservoir that is sufficiently large to enable (a) a high temperature of the recovered water, (b) a large flow rate (i.e., higher injection/production rates), and (c) mitigation and minimization of the inevitable thermal decline caused by the mining of heat by the injected cold water. Water (H2O) is shown to be consistently superior to supercritical CO2 (sCO2) as the heat-exchange (working) fluid, despite some thermophysical properties that appear to make sCO2 a promising candidate. The techno-economical analysis shows that drilling is the main factor increasing the cost of EGS. Thus, significant improvements in drilling efficiency and technologies are necessary to reduce the levelized cost of energy (LCOE) of EGS and make it an attractive energy recovery option
Shock-Driven Multiphase Mixing Physics in High-Speed Flows
No full textThe Shock-Driven Multiphase Instability (SDMI) occurs when a multiphase (particle-gas) medium is instantaneously accelerated by the passage of a shockwave. It has applications in detonation-driven propulsion engines, explosive dispersal of particles, hydrometeor impacts in hypersonic flight, and astrophysics events. The SDMI involves several phenomena that occur concurrently across overlapping length and time scales, from the mesoscales (cloud-scale) to the microscale (particle-scale). At the larger scales, the problem involves turbulent mixing due to acceleration across pressure and density gradients, like the classic Richtmyer-Meshkov Instability; however, including effects of larger particle or droplet sizes results in longer equilibration times and decreased mixing. At the microscale, in the case of liquid droplets, particle-scale mixing occurs due to droplet breakup and evaporation at a high Weber number. The concurrent phenomena under these conditions are complex and poorly understood, warranting research in numerous physical systems.
Considering this, I will present the findings derived from recent experiments that quantify the multiphysics aspects of the SDMI. I will dive into the impact of the particle velocity relaxation time on hydrodynamic evolution to enhance the accuracy mixing predictions from circulation deposition models. Additionally, I will explore particle-scale mixing, encompassing droplet breakup and vaporization, in quasi-1D experiments to gain a deeper understanding of their influence on hydrodynamic mixing. Moreover, I will explore the effects of high particle evaporation rates on multiphase hydrodynamic mixing. Ultimately, this work intends to develop models that accurately predict cloud-mixing time and length scales, as well as the dynamics of particle-scale mixing
Are Open Contacts Associated with Peri-implant Disease?
No full textAims: This study was conducted to determine if open contacts are associated with peri-implant disease. Also, possible associations concerning the width of an open contact as they relate to disease and food impaction were evaluated.
Material and Methods: A clinical exam was performed including: probing depths, interproximal contact status (open vs. closed), microbial sampling from 16 implants, report or observation of food impaction, and review of existing radiographs. This information was used to determine the implant diagnosis. The microbial samples were studied using qPCR. Spearmann���s correlation test was performed to determine whether any associations around the desired variables could be found.
Results: 44 (22 open contacts/ 22 closed contacts) sequential implants in 25 patients were evaluated in the Texas A&M School of Dentistry���s dental clinics. The prevalence of peri-implant mucositis was 22.7%, and the prevalence of peri-implantitis was 11.4%. No statistically significant associations were found between open contacts and peri-implant health status or rate of food impaction. No statistically significant association was found between food impaction and rates of peri-implant disease as well. The width of an open contact also did not impact the health status of the implants or the rates of food impaction. However, peri-implant disease was associated with elevated levels of Peptostreptococcus micros. Also, there was a positive association between the number of Capnocytophaga species bacteria present and the increased width of open contact.
Conclusions: Within the confines of this study open contacts around dental implants are not associated with peri-implant disease. There is a noted increase of Peptostreptococcus micros around diseased dental implants. More research is necessary to corroborate these findings
Integrated Fracture Propagation, Fluid Flow and Geomechanics Modeling for Sealed Wellbore Pressure Analysis
No full textOffset well pressure monitoring is a useful fracture diagnostic tool for detecting pressure changes due to far-field fracture propagation. Recently, sealed wellbore pressure analysis has emerged as a low-cost diagnostic tool for fracture hit detection in unconventional development. The surface pressure gauge is installed in the offset monitor well to monitor pressure changes as hydraulic fractures propagate and intersect the wellbore. A monitor well, in this context, refers to a strategically located observation well situated near the hydraulic fracturing treatment well. It is sealed to ensure a closed system, meaning there are no perforations connected to the formation, thereby preventing fluid flow into or out of the wellbore. Inside the wellbore it is filled with a low compressibility fluid. To extend the understanding of sealed casing response, a methodology of using integrated numerical model to simulate sealed wellbore pressure is established. The objective is to investigate the strain/pressure response along the sealed wellbore under different circumstances of fracture intersection.
In this study, a workflow was presented to model fracture propagation, and estimate resulting far-field strain and pressure changes in the sealed wellbore. The integrated numerical model consists of a commercially available fracture propagation model, a three-dimensional geomechanics model, and a transient fluid flow model. Fracture propagation model is used to simulate fracture geometry and fracture net pressure. The finite element-based fluid flow model and geomechanics model of fractured rock and sealed casing were established for pressure, stress/strain modeling and solve the linear elastic stress-strain-displacement behavior within the simulation domain. Adopting this integrated approach, the internal volume change of the wellbore, and the corresponding surface pressure change can be evaluated to aid in understanding sealed wellbore pressure behavior and far-field fracture interaction.
This study includes various applications of the developed methodology. A field-scale case study and numerical investigation were conducted to interpret field-measured pressure responses during hydraulic fracturing. The model was also applied to simulate strain responses observed in a laboratory fracture experiment with embedded fiber optic cables. The comparison between simulated and measured strains validated the accuracy of the model. Finally, completion parameters were evaluated by analyzing offset wellbore pressure data. This evaluation included comparing the estimated injected volume when the fracture first intersects the offset wellbore and the magnitude of pressure response with various completion parameters such as number of clusters, cluster spacing, injection rate, and injected fluid loading. This evaluation shows the importance of optimizing completion design to enhance fracture stimulation performance
Using Antibiotic Alternative Feed Additives to Improve Overall Duck Growth Performance and Welfare
No full textGrowing ducks with optimal efficiency, health, and welfare has become of paramount importance. While numerous antibiotic alternatives (AA) have been investigated in other poultry species to reach these goals, there has been limited research on Pekin ducks. Several experiments were conducted to determine the effects including (i) organic acids (OA), (ii) oregano oils (OO), and (iii) direct fed microbials (DFM) in ducks. Experiment 1 evaluated duck growth, health, and welfare with water supplementation of OA and OO. The OA and OO improved feed conversion ratio (FCR) and body weight (BW) (P 0.05). Experiment 2 evaluated optimum inclusion rates of a commercially available (DFM) feed additive. Duck growth, stress, fear response, welfare, and litter conditions were evaluated. Results conveyed CON had higher (P 0.05) compared to CON. Experiment 3 evaluated the use of the same treatments as Experiment 2 except for the addition of a prolonged heat stress period added during the grow out. Results indicated BW and FCR compared to CON (P > 0.05) was higher than all other treatments. Total white blood cell counts were lower than CON (P < 0.05) compared to all other treatments in the DFM heat stress trial. Heterophil counts, H/L ratio, and total plasma corticosterone levels were also lower than CON (P < 0.05) compared to all other treatments reviewed whether through water supplementation or dietary supplementation. Lymphocytes counts were higher than CON (P < 0.05) compared to all other treatments. Villus height presented differences (P < 0.05) in all other treatments compared to CON. In conclusion, these experiments indicate that Organic Acid, Oregano Oils, and Direct fed microbials can be used to improve duck growth, feed efficiency, stress susceptibility, and bird welfare
Improving the SPEE Monograph 3 Approach through MLR-Normalization
No full textIn 2008, as part of a modernization effort, the Securities and Exchange Commission (SEC) adopted rules restricting undeveloped reserves to acreage directly offsetting existing wells unless reliable technology could justify greater distances. This rule significantly limited the amount of proved undeveloped (PUD) reserves that could be disclosed in unconventional plays, which require more wells to fully develop than their conventional counterparts. Recognizing the industry's need, the Society of Petroleum Evaluation Engineers (SPEE) published its third monograph in 2010.
The SPEE Monograph 3, while innovative, limited its calculations to estimated ultimate recovery (EUR) normalized by completed lateral length (CLL). It otherwise overlooks other operator-controlled variables, such as completion design, location and well depth, which are shown to have a significant impact on performance.
In the following thesis, I augment the SPEE Monograph 3 approach with multiple linear regression (MLR) models using certain operator-controlled variables from publicly available sources. I generate an equation to explain additional variability in performance and normalize EURs. Finally, I follow the SPEE Monograph 3 recommendations for estimating proved areas and volumes, comparing the results to CLL-normalization alone.
In the Woodford case study, my proposed workflow was shown to reduce minimum analogs required for the initial establishment of reliable technology by 27%, resulting in the booking of PUDs beyond direct offsets 18 months sooner. Additionally, the use of MLR-normalization resulted in proved areas up to 15% larger and proved volumes up to 31% larger than CLL-normalization.
Modern software and data availability make MLR models achievable for operators of all sizes. My work utilized RStudio, a free programming software with many statistical packages, and Enverus, an online subscription service to oil and gas data. With some effort, MLR modeling is programmable, making it easy to integrate into existing PUD workflows
Immunomodulatory Roles of Renal Lymphatic Endothelial Cells in Kidney Injury
No full textAcute Kidney Injury (AKI) is defined as a sudden decrease in renal filtration and is found to be associated with increased risk of developing chronic renal conditions such as Chronic Kidney Disease (CKD) and End-Stage Renal Disease (ESRD). While the mechanisms of the AKI-to-CKD transition remain unclear, AKI associated injury promotes an environment of persistent renal inflammation and fibrotic remodeling which may drive irreversible loss of nephrons and other renal cell types. Inflammation associated lymphangiogenesis (IAL) maintains tissue homeostasis through the uptake of proteins, fluids, macromolecules, and immune cells. IAL occurs upon AKI insult and is driven by Vascular endothelial growth factor D (VEGF-D) and VEGF-C. Recent work has demonstrated lymphatics and their components, lymphatic endothelial cells (LECs), have immunomodulatory roles such as antigen presentation, major histocompatibility complex (MHC) expression, and chemokine receptors. This dissertation investigates how renal lymphangigogenesis and LEC genetic adaptations in various models of kidney injury alter the adaptive immune cells in the kidney and the outcomes of renal function post-injury. Increased renal lymphatic density prior to the onset of kidney injury in a mouse model of kidney specific inducible overexpression of VEGF-D (KidVD) demonstrated an altered CD4:CD8 T cell ratio, decreased fibrotic remodeling, and improved functional recovery. Single cell RNA sequencing (scRNA seq) revealed that after AKI isolated renal LECs have T cell related immunomodulatory roles. To address the direct effect of LEC- T cell interactions, a murine genetic model with a LEC specific deletion of the Sphingosine-1- Phosphate (S1P) transporter Spinster 2 (SPNS2), key for S1P chemokine gradients to direct tissue immune cell egress, revealed altered renal immune cell subtypes and differential responses to injury challenge. Additionally, mice with disrupted LEC-S1P signaling demonstrate increased renal immunoglobulin deposition and, with nephrotoxic serum challenge, increased B cell activation and B effector subtype presence. This dissertation strengthens the connection between lymphangiogenesis and immunomodulation in kidney injury through the alteration of the adaptive immune response and demonstrates lymphatic targeted therapeutics may provide a novel renal targeted treatment option to prevent inflammatory progression to CKD
Essays in Behavioral and Experimental Economics
No full textMy dissertation consists of three independent essays on the topics of behavioral economics, experimental economics, and information economics.
In Chapter 1, we investigate how rule enforcers leverage the options to hide or reveal their privately-informed detection ability and how agents respond utilizing a disclosure game of verifiable information with either transparent or opaque enforcement objectives. When governing entities levy financial penalties for rule violation, they may aim to maximize compliance or revenues. Agents may be uncertain of these objectives; further they may also not know enforcers��� detection ability for rule violation. Our model derives multiple equilibria. To examine the selection among those equilibria, we conduct laboratory experiments where the enforcer���s objective is known to the agent in transparent treatments, but unknown to the agent in the opaque treatment. In transparent treatments, unraveling occurs. However, under the opaque treatment, only compliance-maximizing enforcers with strong detection ability reveal their detection ability, and agents violate the rule when enforcers hide. Our results outline that when the enforcement objective is opaque to agents, strategic withholding information related to the detection ability benefits revenue-maximizing enforcers.
In Chapter 2, we provide the means to have the largest comprehensive standardized test of all such elicitation mechanisms that are strategically-equivalent but cognitively-simpler than the Becker-Degroot-Marschak (BDM) mechanism. The dominant-strategy BDM mechanism is the prevailing mechanism for eliciting individuals��� valuations within economic research. However, recent research has highlighted systematic bidding mistakes under the BDM mechanism. We examine a BDM design for induced-value sellers in a controlled, laboratory environment. Treatments vary across three additional formats of elicitation mechanisms: (1) a descending price clock mechanism that satisfies refinements of dominant strategy, namely obviousness; (2) a BDM mechanism with additional contingent protocols that improves subjects��� understanding of the payoff function; and (3) a dynamic multiple price list with descending prices that simplifies the structure of the game. Our experimental results show that (3) appears to improve the game form misconceptions of the BDM mechanism but cannot improve overall accuracy of bids. Meanwhile, contrary to previous theoretical findings and online experiments, neither (1) nor (2) provides more accurate elicited values than the BDM mechanism in the laboratory.
In Chapter 3, we experimentally examine of two distinct channels influencing market behavior in a post-price mechanism of experienced goods: (1) whether there is a mandatory return option that the buyer can utilize or not, and (2) the degree to which buyers share different perceptions for the range of the random distribution that draws the experienced good���s true value. Previous literature has documented that a mandatory return option increases seller���s uniform price and buyer���s purchasing tendency in online sales platforms. However, limited attention has been given to its effect on experience goods���where the good���s true value is drawn from a random distribution, and only the buyer can learn it after purchase. Our results show that a mandatory return option decreases the seller���s uniform price for the experienced good. Conversely, for experienced goods with more heterogeneous perceptions, such heterogeneity benefits the buyer but hurts the seller. Our findings provide insights regarding the potential negative impacts of a mandatory return option on market behavior, particularly when buyer���s perception about the experienced good���s value varies in terms of its possible range
Catalogs for the TM Members required for the Southern African Eptesicus
No full textBound book, each page corresponds to a karyotype slide data.Data pages for TM37614-TM37953 corresponding to unique identifiers of specimens/samples examined for biological research. Specimens are primarily housed at Texas A&M University; Biodiverstiy Research and Teaching Collection
Integrated Protein Turnover: Toward a New Understanding of Cellular Protein Metabolism
No full textProtein metabolism lies at the heart of cellular health. However, the intersections between protein anabolism and catabolism are not completely understood. Here we propose a new view on cellular protein metabolism, the integrated protein turnover model, which we argue better explains the events and evidence underlying anabolic and catabolic states in cells. Instead of viewing protein synthesis and breakdown as separate pathways, we argue that these processes are fundamentally and inextricably linked, and that overall anabolism and catabolism are the result of simultaneous and coordinated action of all the protein metabolic machinery, encompassing the mTOR, autophagic, and ubiquitin-proteasome pathways. We provide the first direct evidence that autophagy is required for protein synthesis in muscle, such that mTORC1-mediated anabolism cannot occur without input from the autophagic pathway. We further show that expression of a select autophagy gene, ATG4B is high in lung and pancreatic cancers and its expression is associated with mortality. Inhibiting ATG4B suppresses cancer cell growth and protein synthesis, allowing for targeting of both autophagic and anabolic markers of metabolism. Finally, we demonstrate that microRNA are a viable candidate for the regulation of the overall proteostatic network, and that removing select microRNA (mir15a/16) from skeletal muscle activates muscle anabolic signaling, while restoring these same microRNA slows anabolism and growth in cancer. Our results demonstrate the strength of the integrated protein turnover model, and indicate new avenues for both the understanding and targeting of protein metabolism in health and disease